AFDHFO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
1000 AM HST FRI JUL 8 2011

.SYNOPSIS...
STRONG TRADE WINDS DRIVEN BY THE SUBTROPICAL HIGH NORTH OF THE AREA
WILL CONTINUE TODAY WITH A GRADUAL DECREASE EXPECTED THIS WEEKEND.
TRADE WINDS WILL THEN REMAIN MODERATE NEXT WEEK. CLOUDS AND SHOWERS
FOCUS ON WINDWARD/MAUKA AREAS THROUGH THE FORECAST PERIOD WITH MOST
RAIN OCCURRING DURING THE NIGHT AND EARLY MORNINGS. AN UPPER LOW
WILL APPROACH FROM THE EAST ON SATURDAY NIGHT AND THEN PASS JUST
NORTH OF THE ISLAND CHAIN DURING THE FIRST HALF OF NEXT WEEK.
SHOWERS MAY BECOME ENHANCED BY THE UPPER LOW SATURDAY NIGHT THROUGH
TUESDAY.

&&

.DISCUSSION...
A NEARLY STATIONARY 1030 MB SURFACE HIGH IS CENTERED 30N 160W. THIS
HIGH IS DRIVING STRONG TRADE WINDS ACROSS THE HAWAIIAN ISLANDS
TODAY. EARLY MORNING SOUNDINGS SHOWED A INVERSION HEIGHTS AT AROUND
8000 FEET...AND PRECIPITABLE WATER VALUES AT 1.2 INCHES...A BIT MORE
STABLE AND DRIER THAN YESTERDAY. MIDLEVEL WINDS CONTINUE TO BE GUSTY
AS THE MIDLEVEL HIGH REMAINS STRONG AND PARKED ON TOP OF THE SURFACE
HIGH. REPORTS OF 30 TO 40 MPH THE MAUNA KEA SUMMIT OBSERVATORIES
HAVE PROMPTED THE RE-ISSUANCE OF THE HIGH WIND ADVISORY THROUGH
EARLY SATURDAY MORNING FOR THE BIG ISLAND SUMMITS ONLY. SURFACE
WINDS ACROSS THE STATE ARE EXPECTED TO REMAIN STRONG THROUGH
SATURDAY...WITH A WEAKENING EXPECTED TO OCCUR SATURDAY NIGHT THROUGH
MONDAY. HAVE BOOSTED UP WINDS A LITTLE BIT ACROSS THE REST OF THE
ISLANDS IN THE FORECAST FOR TODAY GIVEN THE CURRENT WIND
OBSERVATIONS. PASSING TRADE WIND SHOWERS ARE IN THE FORECAST...BUT
LESS RAIN COVERAGE FROM TODAY AND SATURDAY THAN HAS BEEN OCCURING
OVER THE PAST FEW DAYS. CLOUDS AND SHOWERS FOCUS ON WINDWARD/MAUKA
AREAS THROUGH THE FORECAST PERIOD WITH MOST RAIN OCCURRING DURING
THE NIGHT AND EARLY MORNINGS.

AN UPPER LOW CURRENTLY NEAR 21N 141W WILL APPROACH FROM THE EAST ON
SATURDAY NIGHT AND THEN PASS JUST NORTH OF THE ISLAND CHAIN DURING
THE FIRST HALF OF NEXT WEEK. THE UPPER LEVEL LOW WILL HELP TO
DISRUPT THE TRADE WIND FLOW AS IT SLOWLY DRAGS A MIDLEVEL AND
SURFACE LOW SOUTH OF THE HAWAIIAN ISLANDS...DECREASING THE PRESSURE
GRADIENT ACROSS THE AREA. WINDS ARE EXPECTED TO REMAIN MODERATE FROM
SUNDAY THROUGH MOST OF NEXT WEEK AS A RESULT. MOST OF THE ENERGY AND
LOW LEVEL TROPICAL MOISTURE WILL REMAIN FAR SOUTH OF OUR AREA
THROUGH. HOWEVER...THE TRADE TYPICAL SHOWERS MAY BECOME ENHANCED BY
THE UPPER LOW BEGINNING SATURDAY NIGHT THROUGH TUESDAY. THE GFS AND
ECMWF ARE COMING INTO BETTER ALIGNMENT AS FAR THE UPPER LOW
TRACK...WHICH AT THIS TIME IS EXPECTED TO SLOWLY TRACK FROM EAST OF
THE BIG ISLAND SATURDAY NIGHT TO JUST NORTH OF KAUAI BY WEDNESDAY.
BY WEDNESDAY...MUCH OF THE UPPER LEVEL DYNAMIC ENERGY WILL BE NORTH
OF THE STATE AND WE WILL GO INTO A NORMAL MODERATE TRADE WIND AND
RAINFALL DISTRIBUTION REGIME.

&&

.AVIATION...
DUE TO STRONG TRADES...AIRMET TANGO WILL CONTINUE FOR LOW LEVEL
TURBULENCE FOR AREAS BELOW 080 S THRU W OF MOUNTAINS FOR THE MAIN
HAWAIIAN ISLANDS. ASSOCIATED TRADE SHOWERS WILL BRIEFLY LOWER
CEILINGS AND VISIBILITY TO MVFR CONDITIONS ON WINDWARD TAF SITES.
HOWEVER...VFR CONDITIONS WILL PREVAIL THROUGHOUT THE FORECAST PERIOD.


&&

.MARINE...
THE TRADES MENTIONED ABOVE...COMBINED WITH ELEVATED SEAS CONTINUE TO
BRING SMALL CRAFT ADVISORY /SCA/ CONDITIONS TO ALL HAWAIIAN
WATERS WHICH WILL CONTINUE THROUGH SATURDAY. HEADING INTO SATURDAY
AFTERNOON AND NIGHT...WINDS WILL BE ON THE DECLINE...WHICH WILL
LIKELY RESULT IN SOME AREAS BEING DROPPED FROM THE SCA.

A SOLID S-SSW SWELL IS CURRENTLY IMPACTING SOUTH FACING SHORES OF
ALL ISLANDS AND A HIGH SURF ADVISORY IS IN EFFECT. THIS SWELL IS
PEAKING THIS MORNING AND WILL SLOWLY DECLINE THROUGH THIS WEEKEND...
BUT ADVISORY LEVEL SURF WILL CONTINUE THROUGH SATURDAY. THE ELEVATED
TRADE WINDS WILL ALSO PRODUCE SHORT PERIOD SURF THAT WILL CREATE
ROUGH CONDITIONS ALONG EAST FACING SHORES OF
KAUAI...OAHU...MOLOKAI...MAUI AND THE BIG ISLAND. A HIGH SURF
ADVISORY IS ALSO IN EFFECT ALSO THROUGH SATURDAY FOR EAST FACING
SHORES OF THESE ISLANDS AS A RESULT.


&&

.HFO WATCHES/WARNINGS/ADVISORIES...
HIGH SURF ADVISORY UNTIL 6 PM SATURDAY FOR SOUTH FACING SHORES OF
ALL ISLANDS. HIGH SURF ADVISORY FOR UNTIL 6 PM SATURDAY EAST FACING
SHORES OF KAUAI-OAHU-MOLOKAI-MAUI-THE BIG ISLAND.

WIND ADVISORY UNTIL 6 AM HST SATURDAY FOR BIG ISLAND SUMMITS.

SMALL CRAFT ADVISORY UNTIL 6 PM HST SATURDAY FOR ALL HAWAIIAN
WATERS-


&&

$$